Batiatus

I would run a temporary new turn on wire to the amp from the p4200 just to see if that works. If it don't then maybe something happened to the head unit. Yeah I'd put the stuff your going to be using in there too. Who knows, maybe that amp is finicky.

For the antenna. I know some head units make the antenna stay up even when the radio isn't on so you might not even want it. But there is also a power connecter for the antenna you might not have connected. Really you should be testing the wires to stuff with a multimeter like eknine9 suggests, it can save you a lot of time.

Volume123

Honestly I don't care about the amp/ antenna or sub, I really just want to make sure this 800 dollar head unit is not broken...... I mean, everything works perfectly but the subwoofer outs, but like someone else said, the amp should turn on no matter if connected to the head unit or not, so what wire actually is the turn on wire for the amp? would it be the smallest one? There is one tiny yellow wire coming from the amp, the rest are at least 8 gauge.

Volume123

Another thing, I just took out my amp, it also had two grey small wires bridged the same size as the remote wire, I think maybe this is for the stock sub and the tweeters? I'm really not sure at all though, it seems as if they might be since those arent working... but the aftermarket sub isn't either.... ALSO the stock amp is not in there anymore, I've only seen one completely stock SC with completely stock sound system, and the amp was to the far right in the trunk, that black stock amp is NOT THERE, the old owner told me he was still using the stock amp but either he relocated it for no reason I can think of, or he was just mistaken. He originally told me the stock sub and amp are still working and in there, then the aftermarket sub and amp are also hooked up and the aftermarket pioneer speakers are running off of the head units amp. I'm starting to think the stock sub and aftermarket sub are both being powered off of the aftermarket amp because of these grey wired bridge wires...still have no idea though anyone know whats going on here possibly?

Volume123

bahhhhhhhh this is so damn aggravating!! No one knows what it might be?! I mean there must be some kind of reason why both the automatic antenna, stock sub and tweeters only specifically dont work with this head unit while right when I switch it back to the single din, everything works perfectly!?!?

Volume123

noone knows what it could be??

eknine9

iTrader: (8)

Run your remote turn on to a different 12v source. It should probably work with your new head unit. There is a seperate wire to move the antenna up and down that has current only when tuner is selected. There should be an output wire/pin for antenna on the back of your head unit that you can splice to if the harness isn't working with your new head unit. Check a wiring diagram from Lexus for your year to make sure you splice the right color wire and your head units pamphlet should let you know which wire from the harness is the antenna wire.

We honstly can't really tell you what it could be unless we were to test it ourselves, which is why we're telling you what to test. Go buy a digital multimeter, it will seriously save you a lot of headache and is a must if you are going to do this yourself. You can use it to test your remote/signal wire once and for all with both head units to see if that is correctly what is causing your amp to not turn on.

I believe that your new head unit isn't sending any current through the remote/signal wire. So if you want to try a quick possible fix without buying a DMM, then wire your remote/signal wire somewhere else that is always on when the key is turned towards ignition. The remote signal wire will be a small 16-24 gauge wire coming out of the same side of your amp as the power and ground wire. Easiest place for you to wire it would be to an empty fuse that is hot when the key is in accessory mode. The owners manual should tell you which ones will work, or you can google it for your year and figure out which fuses line up to which amenities and figure out which you don't have and tap into it. For instance if you don't have a car phone, and there is a fuse for the car phone (which there should be) it will be empty and you can tap into that with a fuse tap which you can buy at any autoparts store or Radioshack.

Fix this first and then you can worry about the stock sub and tweeters.
That will not be as easy to diagnose as the remote signal wire, especially if you do not know which wire is going where.

chitown18

check settings you cant check voltages check settings lastly take it to the shop you may be over your head on this one. It is this simple your head unit has an output that is for the remote powering your amp if this is not sending 12 volt output from the head unit and the amp is on in the settings than head unit is no good. Try checking voltage without being connected and then after being connected ( this is where you use that multimeter you already bought lol) good luck. I still believe it might be settings.

Volume123

I think it might be settings as well as I have not used this double din headunit in over a year so there might be something I forgot about. Really all I remember is that there is a subwoofer on and off button which normally used to turn on my amp as well, BUT i just found out from the previous owner that the stock amp IS NOT IN THE CAR anymore... sweet... literally just found it out right now... so the stock tweeters/sub is running off the 2 chan amp as well as the aftermarket sub.... makes a little more sense now but still don't know how I might be able to actually get the stock amp/sub/tweeters/after market sub to work all with this amp with my new headunit

Volume123

Well.. jsut for an update, I have realized my tweeters are obvioulsy hooked up to my 2 chan amp which was running the 10 inch sub as well.. Like I've said before I did not run this setup I purchased the car with the setup already in so I am trying to figure this oout on my own... of course with the help of my friends on CL... and have always done my own setups in cars for systems.